Kohlrabi Companion Plants

Pairing kohlrabi with the right neighbors can improve your entire garden’s health and yield. Understanding kohlrabi companion plants is the first step to a more productive and resilient vegetable patch. This guide will show you which plants to grow alongside your kohlrabi and which to keep far away.

Companion planting is the practice of placing certain plants near each other for mutual benefit. For kohlrabi, a cool-season brassica, good companions can deter pests, improve soil nutrients, and save space. The wrong neighbors, however, can lead to competition and disease. Let’s look at the best allies for your kohlrabi crop.

Excellent Companions For Kohlrabi

These plants offer clear advantages when grown near kohlrabi. They work through pest control, soil improvement, or physical support.

Aromatic Herbs For Pest Repellent

Strong-smelling herbs are fantastic kohlrabi companions. Their powerful scents mask the smell of kohlrabi from common pests like cabbage worms and flea beetles.

Dill: Attracts beneficial wasps that prey on cabbage loopers and other harmful insects.
Rosemary: Its strong aroma confuses and repels a wide array of brassica pests.
Sage: Helps deter cabbage moths, which are a primary threat to kohlrabi leaves.
Thyme: A low-growing herb that forms a living mulch, suppressing weeds while repelling pests.
Chamomile: Known as a “plant doctor,” it can improve the health and flavor of kohlrabi.

Alliums For Natural Pest Deterrence

Plants from the onion family are some of the best companions for kohlrabi. Their pungent odor is a powerful natural pesticide.

Onions: Their smell deters many insects that are attracted to kohlrabi.
Garlic: Repels aphids and Japanese beetles, and may help with fungal issues.
Chives: Deter aphids and can improve kohlrabi’s growth and flavor.
Leeks: Serve a similar function as onions and garlic, occupying a different soil layer.

Flowers That Attract Beneficial Insects

Flowers aren’t just pretty; they’re functional. They lure in insects that eat common kohlrabi pests.

Nasturtiums: A classic trap crop. Aphids prefer them over kohlrabi, drawing pests away. They’re also edible.
Marigolds: Their roots release a substance that suppresses nematodes in the soil. French marigolds are particularly effective.
Calendula: Attracts pollinators and beneficial insects like ladybugs, which consume aphids.
Sweet Alyssum: A low-growing flower that attracts hoverflies, whose larvae are voracious aphid eaters.

Good Vegetable Companions

Certain vegetables grow well with kohlrabi because they have complementary growth patterns and needs.

Beets: A root crop that doesn’t compete with kohlrabi for space, as kohlrabi’s bulb grows above ground.
Leafy Greens (Lettuce, Spinach): These are shallow-rooted and fast-growing, providing ground cover without competing heavily for nutrients.
Cucumbers: Can be grown nearby if you ensure kohlrabi gets enough sun, as their vines spread along the ground.
Celery: May help repel the white cabbage butterfly, a common pest for brassicas.

Plants To Avoid Near Kohlrabi

Just as important as knowing what to plant is knowing what not to plant. Some species are poor companions for kohlrabi due to competition, shared pests, or growth inhibition.

Other Brassicas (Cabbage Family)

This is the most crucial rule. Avoid planting kohlrabi with its close relatives.

Why: They compete for the same exact nutrients (like calcium and phosphorus) and attract the same pests and diseases. Grouping them together creates a target for problems like clubroot, cabbage loopers, and aphids.
Examples: Broccoli, Cauliflower, Brussels Sprouts, Kale, Cabbage, Collard Greens, Rutabaga, Turnips.

It’s best to rotate your kohlrabi so it’s not planted where another brassica grew the previous year, either.

Plants That Stunt Growth

A few specific plants are known to negatively affect kohlrabi’s development.

Pole Beans and Tomatoes: These are often listed as inhibitors for kohlrabi growth, though the exact reason (perhaps allelopathic chemicals or intense nutrient competition) isn’t always clear. It’s safest to keep them separate.
Strawberries: Some gardeners report that strawberries and kohlrabi compete too aggressively and can harbor slugs, which damage both plants.

Heavy Feeders And Space Hogs

Plants that require lots of nutrients or physical space can overwhelm kohlrabi.

Corn, Squash, and Pumpkins: These plants are very heavy feeders and can shade out kohlrabi, which needs full sun to form good bulbs.
Sunflowers: Their tall stature casts too much shade, and their roots are allelopathic, potentially secreting substances that hinder the growth of nearby plants like kohlrabi.

Planning Your Kohlrabi Companion Planting Layout

Knowing the lists is one thing; applying them in your garden is another. Here are practical ways to arrange your kohlrabi and its companions.

Interplanting Strategies

Interplanting means mixing different plants within the same bed or row. This maximizes space and confuses pests.

Herb Borders: Plant a border of rosemary, sage, or thyme around your kohlrabi patch. This creates a fragrant barrier.
Underplanting: Use low-growing companions like lettuce, spinach, or thyme beneath your kohlrabi plants. They act as a living mulch.
Row Alternation: Plant a row of kohlrabi, then a row of onions, then a row of beets. This diversifies the planting and disrupts pest pathways.

Succession Planting With Companions

Kohlrabi is a fast-growing crop. You can plant it before or after other vegetables in the same space.

Spring: Plant kohlrabi with fast-growing lettuce. Harvest the lettuce before the kohlrabi needs the space.
Summer: After harvesting early kohlrabi, plant beans in that space. The beans will fix nitrogen for future crops.
Fall: Follow summer garlic with a planting of kohlrabi. The soil will be pest-free and ready.

Container And Small Space Ideas

You can practice companion planting even in pots or small raised beds.

Plant one kohlrabi in the center of a large container (at least 12 inches deep). Surround it with several chive or onion plants, and edge the pot with creeping thyme.
In a square foot garden, plant kohlrabi in one square. Plant beets or onions in the adjacent squares, and nasturtiums in a nearby corner square to draw away aphids.

The Science Behind The Pairings

Companion planting isn’t just garden lore; much of it has scientific explanations. Understanding the “why” helps you make better decisions.

Pest Confusion And Trap Cropping

Pests often find their host plants by smell. A monoculture of kohlrabi sends a strong, clear signal. Adding strong-smelling herbs and alliums masks that scent, making it harder for pests to find your crops. Trap crops like nasturtiums are even more sacrificial—they are more attractive to the pest, luring them away from your kohlrabi entirely.

Beneficial Insect Attraction

Many companion flowers produce nectar and pollen that sustain adult beneficial insects. For example, hoverflies and parasitic wasps need this food source. Once attracted to the garden by the flowers, they lay their eggs. Their larvae then consume vast quantities of aphids, caterpillars, and other pests. This creates a natural, self-sustaining pest control system.

Root Interactions And Soil Health

Roots communicate and interact. Marigolds release alpha-terthienyl, a compound that suppresses root-knot nematodes. Legumes like beans fix atmospheric nitrogen, but since they are poor companions, its best to use them in rotation after kohlrabi. Deep-rooted companions can bring up nutrients from lower soil layers.

Common Kohlrabi Problems And Companion Solutions

Use companion planting as a tool to address specific issues you might encounter while growing kohlrabi.

Preventing Cabbage Worm Damage

Cabbage white butterflies lay eggs that become voracious green caterpillars.

Companion Solution: Interplant with sage, thyme, or rosemary to disguise the kohlrabi’s scent. Grow nasturtiums as a trap crop on the garden’s edge. Plant dill and sweet alyssum to attract parasitic wasps that target the caterpillars.

Deterring Aphid Infestations

Aphids can cluster on the undersides of kohlrabi leaves, stunting growth.

Companion Solution: Chives and garlic are excellent deterrents. Plant calendula and sweet alyssum to attract ladybugs and lacewings, which can eat dozens of aphids per day.

Improving Bulb Formation

For a tender, well-formed kohlrabi bulb, the plant needs consistent moisture and nutrient access without excessive competition.

Companion Solution: Use shallow-rooted lettuce or spinach as a living mulch to conserve soil moisture. Avoid planting with heavy feeders like corn or squash. Ensure companions are not shading the kohlrabi.

Frequently Asked Questions

Can You Plant Kohlrabi Next To Tomatoes?

It is generally not recommended. Tomatoes and kohlrabi are both heavy feeders, competing for nutrients. Some evidence also suggests tomatoes can inhibit the growth of brassicas like kohlrabi. For the best results, keep them in separate garden sections.

What Are The Best Companion Plants For Kohlrabi In The Fall?

Fall kohlrabi benefits from many of the same companions. Focus on quick-growing partners that thrive in cooler weather. Excellent choices include beets, lettuce, spinach, and green onions. You can also keep aromatic herbs like rosemary and thyme nearby until the first hard frost.

Is It Okay To Plant Kohlrabi With Peppers?

Peppers and kohlrabi are generally considered neutral companions. They don’t directly harm each other, but they don’t provide significant benefits either. You can plant them nearby if space allows, but ensure the peppers do not grow tall enough to shade the sun-loving kohlrabi.

How Far Apart Should Kohlrabi Be From Bad Companions?

A good rule is to separate kohlrabi from incompatible plants like other brassicas, tomatoes, and strawberries by at least 3 to 4 feet. If possible, place them in different raised beds or garden rows. Crop rotation from year to year is equally important to prevent soil-borne disease buildup.

Can I Plant Kohlrabi With Carrots?

Yes, carrots and kohlrabi can be good companions. They occupy different soil spaces—kohlrabi’s bulb forms at the soil surface, while carrots grow deep underground. This minimizes root competition. Their different growth habits make them suitable for interplanting in the same row.